Nerve and small vessel repair are important, widely used medical techniques. Current technologies do not allow imaging to be performed below the tissue surface, so that the alignment of fascicles or vessel layers can not be established. Misalignment is one of the major reasons that the results of nerve repair are currently poor. Similarly, with small vessel repair, intimal flap and adventitial inversions, which can not be detected from the surface, can lead to subacute vascular occlusion. Optical coherence tomography (OCT) is a recently developed high resolution imaging modality. OCT is analogous to ultrasound, measuring the intensity of backreflected infrared light rather than sound. The resolution of OCT is between 2-20 mum, up to 25X higher than anything available in clinical medicine. In addition to it's high resolution, advantages of OCT include its high data acquisition rate, compact portable size, the small inexpensive probes, and the ability to be combine with various forms of spectroscopy. The hypothesis of this work is that OCT can be used to improve the outcome of nerve and small vessel repair. The hypothesis will be tested with the following specific aims: 1. Develop a clinically viable hand held probe, 2. Development of an all digital Doppler system, 3. Investigate structural and Doppler OCT for vascular repair in vitro, 4. Investigate structural and Doppler OCT for vascular repair in vivo, 5. Perform studies comparing OCT and Conventional surgical microscopy in vivo, 6. Use structural, polarization, and spectroscopic data to identify sensor vs motor nerves, and 7. guide epineural nerve repair with OCT guidance.